The present invention is directed to an apparatus for forming a fluid conveying pipe known in the trade as a "double ended upset pipe". Such a pipe has a forward, or "pin" end section, an elongated middle section and a rearward, or "box" end section. The inner diameters of all three sections of the pipe are the same. The outer diameters of the forward and rearward end sections of the pipe are substantially greater than the outer diameter of the middle section of pipe. Therefore, the thickness of the middle section of the pipe is substantially thinner than either of the forward and rearward end sections of the pipe. The extra thickness of the forward and rearward end section of the pipe is machined and/or threaded to enable the forward, or "pin" end of a first pipe to be coupled to the rearward or "box" end of a second pipe.
In the past, metallic double ended upset pipes have been formed by extruding the middle and end sections of the pipe separately and welding the forward and rearward end sections to opposite ends of the middle section. Since the welded areas represent potentially weak areas of the pipe, each section of the pipe is made thicker than that which would normally be needed. This procedure is time consuming and expensive. The extra thickness which requires extra material also adds a material cost to the pipe. The added weight of the pipe adds still further costs in shipping and handling.
Many metal extrusion devices and methods have been developed for extruding a pipe from a billet with the use of a press, a die, and a mandrel. However, there is no known apparatus or system for extruding an integral pipe having a uniform inside diameter in which the opposite end sections of the pipe have an outside diameter greater than the outside diameter of the middle section of the pipe. These and other difficulties experienced with the prior art pipe extruding devices or methods have been obviated by the present invention.
It is, therefore, a principal object of the invention to provide an apparatus for extruding a pipe from a metal billet for producing an integrally formed pipe having a constant or uniform inside diameter and a middle section which has a smaller outside diameter than the outside diameter of each of the opposite end section of the pipe.
A further object of the invention is the provision of an apparatus for extruding a pipe from a metal billet as described above in a single continuous extrusion operation.
Another object of the present invention is the provision of a method of extruding a pipe from a metal billet in which the pipe has uniform inside diameter and a middle section having a smaller outside diameter than the outside diameter of the opposite end sections of the pipe.
A still further object of the invention is the provision of a method of extruding from a metal billet a pipe as defined above in a single continuous process.
Still another object of the invention is the provision of having an outside non-uniform configuration mandrel for use in a metal extrusion machine for extruding from a metal billet a pipe having a uniform inside diameter and a middle section which has a smaller outside diameter than the outside diameter of the opposite end sections of the pipe.
Another object of the invention is the provision of an apparatus for extruding a pipe from a metal billet wherein the middle section of the pipe has a smaller outside diameter than the outside diameter of each of the opposite end sections of the pipe and one end section of the pipe has a smaller inner diameter that the inner diameter of the middle section and opposite end section of the pipe.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.